The development of antibiotics against drug resistant gram negative bacteria (GNB) is a central problem in medicine. Developing antibiotics against GNB has been challenging because of their low membrane permeability, which prevents antibiotics from reaching therapeutic concentrations within GNB. The objective of this proposal is to develop a new strategy for enhancing the transport of antibiotics into GNB, via conjugation to thiomaltose. Thiomaltose conjugated antibiotics have internalization rates into GNB that are dramatically enhanced over free antibiotics because they enter bacteria via maltodextrin and other oligosaccharide transporters, which are the preferred food source for bacteria. In addition, mammalian cells do not express maltodextrin and oligosaccharide transporters, and therefore thiomaltose conjugated antibiotics should not enter mammalian cells and should have a much higher therapeutic window than free antibiotics. The experiments in this proposal will investigate if the efficacy of the drug radezolid can be improved by conjugating it to thiomaltose. The central hypothesis of this proposal is that: Radezolid conjugated to thiomaltose, termed TMR, will have a wider therapeutic window than free radezolid at treating drug resistant GNB, due to its enhanced transport and lower toxicity. This hypothesis is based on our preliminary data, which demonstrates that thiomaltose-conjugated radezolid is at least 2 orders of magnitude more effective at treating drug resistant P. aeruginosa than free radezolid. We will test the central hypothesis of this proposal by completing the following Specific Aims: R21 Phase Specific Aim 1. Increase the transport of radezolid into drug resistant GNB via conjugation to thiomaltose Specific Aim 2. Increase the efficacy of radezolid via conjugation to thiomaltose R33 Phase Specific Aim 1. Increase the in vivo efficacy of radezolid against GNB via conjugation to thiomaltose Specific Aim 2. Pharmacokinetics of TMR and optimization of its oral bioavailability The experiments in this proposal are innovative because they develop a strategy, which can target antibiotics to GNB and increase their therapeutic window. The experiments in this proposal are significant because they will lead to the development of new therapeutics for drug resistant GNB.